Cut/mask multiple planes along a circle at once
Make sure all your objects's origins are in the center of the world. Go into Object mode, SHIFT + C to center the 3D cursor, then A to select all, Right Click > Set Origin > To 3D cursor. 

Also, apply the scale transform with CTRL + A > Scale or go to Object > Apply > Scale

Give this material to all your objects (only the alpha part is important):



The "Length" node is obtained by using a "Vector Math" node and set the operation accordingly. Similarly for the "Greater than" node, you must first add a "Math" node and change the operation.

To give this material to all your objects, give it to one of them, then select them all with A and SHIFT click on the object with the material. Then go to Object > Make Links > Materials or SHIFT + C > Materials

If you use Eevee, make sure to set the alpha blend mode to clip :



Tweak the Math node threshold :



You can then add a driver to use your bezier circle as a visual guide, and mask the bars under it when you scale it :